Because of their durability and cost-effectiveness, mechanically stabilized earth structures, or earth masses, have been used routinely for many years in various applications in highway projects such as for walls, embankments, bridge abutments, roadway supports, and others. Often, facing walls are used in conjunction with the earth masses to provide a forming surface during the placement of the fill and reinforcements used to construct the mass. The facing walls retain the earth mass after construction to protect the mass from erosion and to protect fabric reinforcements from UV degradation. The facing walls also often serve the purpose of providing an aesthetically pleasing cover for the earth masses.
Various facing walls and wall assembly methods are presently known and used in the constructions of earth mass (fill) structures. A facing panel system used as a restraining form primarily for cement structures is disclosed in U.S. Pat. No. 4,564,316 to Hunziker. The method and facing panel system include a cantilever support which couples two vertically adjacent panels. Cementitious fill is placed behind the lower panel and allowed to solidify. The lower panel is secured to the solidified cementitious fill by a rigid tie-back anchor to form a monolithic mass. The cantilever support transfers horizontal loads exerted on the upper panel as fill material is placed behind the panel back through to the fill mass via the lower panel. In one embodiment, external strongbacks are used to provide the cantilever support; in another embodiment the cantilever support is internal. Vertical adjustment means are provided in both embodiments. For the internal support, the vertical adjustment takes place from behind the panels and is thereby limited to adjustment during wall construction only. For the external support, the vertical adjustment takes place from the front of the panels during the construction of the wall. However, this means is not part of the facing wall structure itself, and no vertical adjustment of the panels can take place once the wall is completed. Neither shifts in the cementitious fill, nor panels response thereto, is addressed in Hunziker. Because the facing wall is rigidly anchored to the cementitious fill, it becomes a fixed monolithic structure with the solidified fill after construction of the wall.
A retaining wall utilizing a compacted granular fill earth mass and facing front panels is disclosed in U.S. Pat. No. 4,961,673 to Pagano et al. The granular fill earth mass includes a plurality of elongated tensile strips to increase the coherency of the mass. The mass also includes grid-form reinforcements having an L-shaped cross-section. Attachment clips attach the tensile strips to the grid forms. The retaining wall also utilizes facing panels having reinforcing members, tensile member extensions, connecting members, and generally parallel layers of concrete between the front face of the fill mass and the back surface of the panels. The tensile member extensions and connecting members form a mechanical linkage to connect the reinforcing members to the tensile strips. The connecting members also may be adjustable, in a manner similar to a turnbuckle, to adjust for various spacings between the rigid reinforcing members and the tensile strips. Concrete layers are poured over the connections and entirely fill a space between the back of the panels and the front of the earth mass. The Pagano retaining wall focusses on the problem of strains placed upon the facing wall, and the adverse affect to the planar appearance to the wall caused thereby, during post construction compaction of the earth mass. It solves the problem by maintaining the deformability of the structure within the grids and the tensile strips inside the earth fill mass, which are capable of straining in response to consolidation of the earth mass. The deformability is, however, localized solely to within the earth mass itself by the provision of the concrete layers between the facing wall and the fill mass. The facing front panels are, thus, divorced from the strains due to consolidation of the earth mass and remain fixed and rigid by becoming part of the monolithic mass of solidified concrete. While suited for its intended purpose, the Pagano wall requires extra material and steps to construct a facing wall which is not adversely effected by the consolidation of the earth mass.
U.S. Pat. No. 5,028,172 to Wilson, et al., discloses a soil reinforcing structure including a planar wall member and at least one grid member horizontally permanently connected to the wall member. The grid member, either in itself or in connection with another grid, acts as an earth mass reinforcement. The grid member, is resiliently flexible, ie., capable of being rolled up, or restorably folded, against the rear surface of the wall member for ease of storage and transportation. Also provided is a connecting grid which interconnects two anchoring grids. The Wilson structure provides an improved means of connecting anchoring grids wherein the connection is easy to facilitate and is easily adapted to commercially available large precast panels.
U.S. Pat. No. 4,440,527 and U.S. Pat. No. 4,790,690 to Vidal, et al disclose wet environment and under water stabilized earth walls and the construction thereof. The earth walls include facing panels which have reinforcing members which are pivotally hingedly mounted thereon so that the reinforcing members can be lowered in a vertical plane onto the top of a lift of particulate material. Other related patents are: U.S. Pat. No. 1,762,343 to Munster; U.S. Pat. No. 4,929,125 to Hilfiker; and U.S. Pat. No. 3,686,873 to Vidal.
As is seen from the prior art, two types of facing walls have been developed for use with earth masses. The first type use earth reinforcements, such as geofabrics, geomats, geobars, and geogrids, all of which are flexible, to connect the wall to the earth mass and to stabilize the earth mass. The other type use rigid anchoring, such as tie-back anchors, as rigid reinforcement for the earth mass and to connect the earth mass to the facing wall. However, the stabilized earth masses tend to deform both during and after construction. Post construction deformations, as discussed in Pagano, et al. is caused by the compaction of granular fill material. Deformations during construction occur as the reinforcements for the earth mass are mobilized. The deformations are particularly experienced at the front face of the earth mass. A need exists for a simple and efficient retaining wall which can accommodate deformations in an earth wall both during and after construction to minimize lateral stresses imposed on the facing panels and resulting bulges in the planar surfaces of the facing panels. A further need exists for the capability of manually adjusting the panels after construction of the wall has been completed.
It is a purpose of the present invention to provide an retaining wall built from a number of facing panels wherein the facing panels are articulated and modular.
It is a further purpose of the present invention to provide such a wall including a number of horizontal joints between panels wherein the panels have a first degree of articulation by being capable of tilting in response to horizontal deformations in the earth mass.
It is a further purpose of the present invention to provide such a wall including a number of vertical joints between panels wherein the panels have a second degree of articulation by being capable of slipping and rotating relative to each other in response to non-uniform deformations in the earth mass which allows the facing panels to further accommodate shifts in the earth mass.
It is a further object of the present invention achieve the first degree of articulation by providing horizontally deformable, or flexible, anchoring between the facing panels and the earth mass to limit restraining anchoring forces.
It is a further object of the present invention to provide retaining wall wherein the panel alignment can be conveniently adjusted after the construction of the earth mass is complete.